Ink for a display panel and method for producing plasma display panel using the ink

ABSTRACT

An ink for a display panel effective in reducing the uneven adhesion of the ink is applied by an ink application apparatus using an inkjet method to form a structural layer (e.g. reflective layer, phosphor layer) of a display panel such as a plasma display panel. The ink is delivered through a nozzle of the ink application apparatus and includes a powder material used in forming the structural layer, water or a water-miscible solvent, a binder formed from a water-soluble resin, and a plasticizer. The flexibility retained by the ink, even after the ink is applied, allows for leveling of the applied ink to occur and uneven adhesion to be reduced as a result.

TECHNICAL FIELD

[0001] The present invention relates generally to display panels such asplasma display panels and liquid crystal display panels, and moreparticularly to reducing the uneven adhesion of an ink for displaypanels applied in forming structural layers of the display panels.

BACKGROUND ART

[0002] In recent years, thin lightweight display devices such as liquidcrystal displays (LCD) and plasma display panels (PDP) have attractedmuch attention for their applicability in computer and television imagedisplay. In particular, the responsiveness, wide viewing angle, andsuitability for large-screen application of PDPs have resulted inwidespread moves in industry and research to secure a market for PDPs.

[0003] A PDP is formed from a front glass substrate having a pluralityof display electrodes and a back glass substrate having a plurality ofaddress electrodes. The front and back glass substrates are arrangedparallel to and facing one another, and a plurality of barrier ribs areprovided in a stripe-pattern therebetween. Phosphor layers in the orderred (R), green (G), and blue (B) are formed in the gap (“rib gap”)between adjacent barrier ribs, and the gaps are filled with a dischargegas.

[0004] Image display in the PDP is achieved when ultraviolet light,which is emitted as a result of a discharge generated when a drivecircuit is used to apply a voltage to the electrodes, strikes thephosphor particles of the phosphor layers and excites them to emitvisible light.

[0005] The phosphor layers are commonly formed using a screen-printingmethod, in which the rib gap between adjacent ribs is filled with aphosphor ink, and the ink is then baked. However, this screen-printingmethod is not readily applicable in the manufacture of PDPs in which thewidth of the rib gap has been reduced in response to demands in recentyears for higher definition image display. In a full specification(1920×1125 pixels) 42-inch high definition (HD) PDP, for example, therib pitch is a fine 0.1 mm to 0.15 mm, and when a thickness of thebarrier ribs is taken into account, a narrow rib gap of 0.08 mm to 0.1mm remains within which to apply the ink. Since the phosphor inkconventionally used in screen-printing has a high viscosity running intotens of thousands of centipoises, accurately applying the phosphor inkin a narrow rib gap at a high speed is not easily achieved.

[0006] Alternative methods for forming the phosphor layers include aphotoresist film method, a photoresist ink method, and an inkjet method.

[0007] According to the photoresist film and ink methods, either a filmis embedded or an ink is applied in the rib gap between adjacent barrierribs. The film and the ink are both formed from a photosensitiveultraviolet resin that includes RGB phosphors. After the film isembedded or the film is applied, the areas of film or ink that will formthe phosphor layers are exposed and developed, while the unexposed filmor ink is washed away. According to both these methods, the phosphorlayers can be formed in the rib gaps with a reasonable degree ofaccuracy, even when the barrier ribs are finely pitched.

[0008] However, in addition to manufacturing complications resultingfrom the embedding/applying, exposing, developing, and washing having tobe conducted sequentially for each of the three colors RGB, there is theproblem of the colors easily becoming mixed. Moreover, because of therelatively high cost of the phosphors and the difficulties involved incollecting phosphors washed away during the washing process, thephotoresist film and ink methods are expensive to implement.

[0009] In comparison, according to an inkjet method as disclosed inunexamined patent application publications 53-79371 and 8-162019 filedin Japan, an ink formed from a phosphor material and an organic binderis discharged under pressure though a plurality of nozzles of an inkapplication apparatus while scanning up and down to apply the ink in thedesired pattern.

[0010] This inkjet method allows for the phosphor ink to be appliedaccurately within a desired rib gap, and therefore provides a simple andcost effective means of forming the phosphor layers that dispenses withthe exposure and washing processes required in the photoresist methods.

[0011] The phosphor ink conventionally used in the inkjet method is amixture of an organic binder (ethyl cellulose, acrylic resin, orpolyvinyl alcohol, etc.), a solvent (terpineol, butyl carbitol acetate,etc.), and phosphor particles.

[0012] However, the comparatively high dielectric constant of theorganic binder and the solvent results in the ink becoming charged fromthe shearing stress that occurs when the ink passes through the tubingand nozzle parts of the ink application apparatus. As a result, the inkflows discharged from the plurality of nozzles react with each other,causing dispersion in the delivery of the ink. Consequently, thephosphor ink is applied and adheres in an uneven manner. In order toimprove brightness in a PDP it is important that the phosphor layers beapplied evenly to the walls and base of the gap between adjacent barrierribs, although this is difficult to achieve with the conventional inkjetmethod described above.

[0013] Apart from phosphor ink, the inkjet method can also be employedto apply inks that include particles used in forming structural layersof the PDP other than the phosphor layers. Examples of such particlesinclude silver particles used in forming silver electrodes anddielectric glass particles used in forming dielectric layers. However,since these alternative inks also include the solvents and organicbinders described above, there remains the problem of the unevenadhesion of the ink resulting from dispersion in the ink delivery aswell as reductions in the solvent concentrations in the ink.

DISCLOSURE OF THE INVENTION

[0014] In view of the issues discussed above, an object of the presentinvention is to provide an ink for a display panel that reduces theuneven adhesion of the ink, even when there is a reduction in theconcentrations of solvent in the ink.

[0015] An ink provided to achieve the above object is applied to adisplay panel substrate using an inkjet method and includes a powdermaterial used in forming a structural layer of the display panel, wateror a water-miscible solvent, a binder formed from a water-soluble resin,and a plasticizer.

[0016] The ink thus provided is effective in reducing the unevenadhesion of the ink by preventing the charging and consequent unevenflow of the ink discharged from a nozzle of an ink application apparatususing the inkjet method. The charging of the ink is prevented by theconductivity of the ink, which results from the water absorbingqualities of the solvent allowing the ink to absorb moisture from theair. However, because of the force of the inkjet discharge, thereremains the problem of the phosphor ink applied in the rib gaps forminga film that is thicker on the sides of each rib gap than on the base.When the ink is applied, the solvent included in the ink disperses intothe porous rib walls, and the concentrations of solvent in the ink arereduced as a result. The viscosity of the ink thus increases, causingthe ink to harden on the rib walls before much of the ink has a chanceto flow down to the base of the gap. As such, phosphor layers are formedin the rib gaps that are thicker on the rib walls than on the base. In aPDP, this causes a reduction in the cell aperture ratio, and asubsequent reduction in brightness. However, the plasticizer included inthe ink of the present invention serves to counter this tendency.Including the plasticizer allows for leveling of the ink to occur for anextended period of time. This is because of the considerable amounts ofplasticizer remaining in the resin component after the ink is applied,even when the solvent concentrations have been reduced throughdispersion and evaporation. Uneven adhesion of the applied ink can thusbe suppressed.

[0017] The ink will be of a suitable viscosity for use in the inkjetmethod if the binder is included in a range of 1 wt % to 20 wt %inclusive of the ink at the time of application.

[0018] The ink will remain at a viscosity that facilitates the levelingprocess after the ink is applied if the plasticizer is included in arange of 0.5 wt % to 10 wt % inclusive of the ink at the time ofapplication.

[0019] The water-soluble resin may include at least one member selectedfrom the group consisting of hydroxypropyl cellulose, ethylhydroxyethylcellulose, carboxymethyl cellulose, polyvinyl alcohol, and polyvinylether, and the weight-average molecular weight of the resin preferablyshould be in a range of 30,000 to 100,000 inclusive.

[0020] The viscosity of a water-soluble resin in solution form isgenerally dependant on its weight-average molecular weight, and therange given above allows for an optimal viscosity of the ink to beachieved at the time of application. Furthermore, a water-soluble resinincluding at least one of the above resins is suitable as the binderbecause almost no residue remains after the baking process, even atconventional baking temperatures.

[0021] The water-miscible solvent may include at least one memberselected from the group consisting of ethylene glycol, ethylene glycolmonoacetate, ethylene glycol monoethyl ether, ethylene glycol monobutylether, ethylene glycol monomethyl ether, ethylene glycol monomethylether acetate, 3-methoxy-3-methylbutanol, allylalcohol, isopropylalcohol, ethanol, glycidol, tetrahydrofurfuryl alcohol, t-buthanol,furfuryl alcohol, propargyl alcohol, 1-propanol, methanol,3-methyl-1-butyne-3-ol, 15-crown-5, 18-crown-6, propylene oxide,1,4-dioxane, dipropyl ether, dimethyl ether, tetrahydrofuran,acetaldehyde, diacetone alcohol, methyl lactate, γ-butyl lactone,glycerin, glycerin-1,2-dimethyl ether, glycerin-1,3-dimethyl ether,glycerin-1-acetate, 2-chloro-1,3-propanediol, 3-chloro-1,2-propanediol,diethylene glycol, diethylene glycol ethyl methyl ether, diethyleneglycol chlorohydrin, diethylene glycol diacetate, diethylene glycoldiethyl ether, diethylene glycol dimethyl ether, diethylene glycolmonomethyl ether, dipropylene glycol, dipropylene glycol monomethylether, and triethylene glycol.

[0022] The plasticizer may include at least one member selected from thegroup consisting of dimethyl phthalate, diethyl phthalate, dibutylphthalate, diheptyl phthalate, di-n-octyl phthalate, di-2-ethylhexylphthalate, octyldecyl phthalate, diisodecyl phthalate, and butylbenzylphthalate.

[0023] The above object may also be achieved by a manufacturing methodfor a plasma display panel that includes a first panel and a secondpanel, the method having a structural layer formation step of forming astructural layer of the first panel, and a sealing step of sealing thefirst panel to the second panel and filling a space between the sealedpanels with a gas medium. The structural layer formation step includesan application substep of applying an ink for a display panel to thefirst panel using an inkjet method, the ink including a powder materialused in forming the structural layer, water or a water-miscible solvent,a binder formed from a water-soluble resin, and a plasticizer; and abaking substep of burning-off the binder and the plasticizer included inthe applied ink.

[0024] According to this method for manufacturing the PDP, the inkretains flexibility after the ink is applied because of the plasticizerremaining in the ink, despite any dispersion or evaporation of thesolvent that might occur. The uneven formation of the structural layercan thus be suppressed, since the retained flexibility of the ink allowsthe leveling process to occur over a prolonged period on time.

BRIEF DESCRIPTION OF DRAWINGS

[0025]FIG. 1 is a partial cross-sectional perspective view of a PDPaccording to an embodiment of the present invention;

[0026]FIG. 2 is a partial cross-sectional view along a y-axis of the PDPin FIG. 1;

[0027]FIG. 3 is a partial cross-sectional view along an x-axis of thePDP in FIG. 1;

[0028]FIG. 4 shows drive circuits mounted in the PDP;

[0029]FIG. 5 is a schematic structural view of an ink applicationapparatus used in forming a reflective layer and a phosphor layer of thePDP;

[0030] FIGS. 6A-6D are enlarged cross-sectional views of a main sectionof a back panel of the PDP showing the processes involved in forming thereflective and phosphor layers; and

[0031]FIGS. 7A and 7B show an application pattern of the ink used informing a silver electrode of the PDP according to a variation of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0032]FIG. 1 is a partial cross-sectional perspective view of a PDPaccording to an embodiment of the present invention. FIG. 2 is a partialcross-sectional view along the y-axis of the PDP in FIG. 1. FIG. 3 is apartial cross-sectional view along the x-axis of the PDP in FIG. 1. InFIGS. 1 to 3, the z direction corresponds to a thickness of the PDP, andthe x-y plane lies parallel to the panel surface of the PDP.

[0033] As shown in FIG. 1, the PDP comprises a front panel 10 and a backpanel 20 arranged to face each other.

[0034] Front panel 10 includes a front glass substrate 11, shading films12, plural pairs of display electrodes 13 and 14, a dielectric layer 15,and a protective layer 16. The pairs of display electrodes 13 and 14 arearranged on the facing surface of front panel 10, and shading films 12are interposed between the display electrodes and front panel 10.Dielectric layer 15 and protective layer 16 are formed, in the statedorder, on the facing surface of front panel 10 so as to cover the pairsof display electrodes.

[0035] Front glass substrate 11 is a flat substrate formed from a sodiumborosilicate glass material, and is provided on the display side offront panel 10.

[0036] As shown in FIG. 3, shading films 12 are formed in a stripepattern on front glass substrate 11, and are composed of frit glass anda black pigment that includes at least one member selected from thegroup consisting of RuO, NiO, TiO, TiO—Al₂O₃, and iron oxide. Shadingfilms 12 serve to prevent glare caused by irradiated light from displayelectrodes 13 and 14 reflecting through front glass substrate 11 to thedisplay side of front panel 10.

[0037] Display electrodes 13 and 14 are laminated on top of shadingfilms 12, and a main component of the electrodes is silver (herein, a“main component” refers to 50 wt % of gross weight or greater). Apartfrom silver, it is alternatively possible to use metals such as gold,copper, chromium, nickel, and platinum as a main component of electrodes13 and 14. Also, in order to secure a wide surface area in a cell, acombination electrode structure can be used in which a narrow silverelectrode is laminated on top of a wide transparent electrode composedof a dielectric metal oxide such as ITO (indium tin oxide), SnO₂, orZnO.

[0038] Dielectric layer 15 is formed so as to cover and thereby insulatedisplay electrodes 13 and 14, and is composed of a glass component suchas a lead oxide glass or a bismuth oxide glass. The lead oxide glass isa compound of materials such as lead oxide, boric oxide, silicon oxide,and aluminum oxide, and the bismuth oxide glass is a compound ofmaterials such as bismuth oxide, zinc oxide, boric oxide, silicon oxide,and calcium oxide.

[0039] Protective layer 16 is formed so as to cover dielectric layer 15,and is composed of materials such as magnesium oxide (MgO), the MgObeing formed in a (111) crystal orientation.

[0040] Returning to FIG. 1, back panel 20 includes a back glasssubstrate 21, address electrodes 22, a dielectric layer 23, barrier ribs24, a reflective layer 25, and phosphor layers 26R, 26G, and 26B.

[0041] Back glass substrate 21 is, similar to front glass substrate 11,a flat substrate formed from a sodium borosilicate glass material. Asshown in FIG. 2, address electrodes 22 are provided in a stripe patternon the facing surface of back glass substrate 21.

[0042] Similar to display electrodes 13 and 14, a main component ofaddress electrodes 22 is silver, and dielectric layer 23 is formed so asto cover and thereby insulate the address electrodes.

[0043] Dielectric layer 23 is a dielectric glass layer composed of thesame glass component used to form dielectric layer 15 on front panel 10.

[0044] Reflective layer 25 is formed so as to cover the base and sidesof the gap between adjacent barrier ribs 24 in which the phosphor layer26B will be formed, and can be composed, for example, of a titaniumoxide and the same glass component used to form dielectric layer 15.Reflective layer 25 serves both as a dielectric layer and also toreflect the visible light generated by phosphor layer 26B. The provisionof reflective layer 25 to reflect the blue light generated by phosphorlayer 26B helps to boost the relatively low brightness of the bluephosphor particles. In order to boost the overall brightness of the PDP,it is possible for reflective layer 25 to be provided in the rib gapscorresponding to not only phosphor layer 26B but also phosphor layers26R and 26G.

[0045] Phosphor layers 26R, 26G, and 26B are formed from the bindingtogether of phosphor particles corresponding to the colors red (R),green (G), and blue (B), respectively.

[0046] Front panel 10 and back panel 20 are fixed together and theperimeter of the panels is sealed using a sealing layer (not depicted)formed from frit glass. Spaces between the sealed front and back panelsare then filled at a predetermined pressure (e.g. 66.5-106 kPa) with adischarge gas (e.g. a gas mixture of 95 wt % neon and 5 wt % xenon) toform discharge spaces 27.

[0047] Whereas display electrodes 13 and 14 extend continuously from oneend of the panel to the other, address electrodes 22 have, as shown inFIG. 4, a break in the middle that allows for duel scanning to beconducted.

[0048] Manufacturing Method for a PDP

[0049] Described below is a method for manufacturing a PDP.

[0050] 1. Manufacture of Front Panel 10

[0051] In manufacturing front panel 10, display electrodes 13 and 14 areformed on front glass substrate 11 with shading films 12 interposedtherebetween. Lead-based dielectric layer 15 is then coated over thedisplay electrodes, and protective layer 16 is coated in turn overdielectric layer 15.

[0052] Shading films 12 are formed by using a screen-printing method toapply a paste composed of frit glass and a black pigment containing RuO,for example, in a stripe pattern to front glass substrate 11, and thenbaking the applied paste composite.

[0053] Display electrodes 13 and 14 include a silver component, and areformed by using the screen-printing method to apply a silver electrodepaste on the shading films 12, and then baking the applied silverelectrode paste.

[0054] Dielectric layer 15 is formed at a thickness of approximately 20μm by using the screen-printing method to apply a composite paste overthe display electrodes, and then baking the applied composite paste at520° C. for 20 minutes. In addition to an organic binder (α-terpineolwith 10 wt % ethyl cellulose dissolved therein), the composite paste maycontain, for example, 70 wt % lead oxide (PbO), 15 wt % boron oxide(B₂O₃), 10 wt % silicon oxide (SiO₂), and 5 wt % aluminum oxide.

[0055] Protective layer 16 is composed of a magnesium oxide (MgO), andalthough a spattering method is conventionally used to form layer 16, inthe present invention a CVD method is used to form layer 16 at athickness of 1.0 μm. The formation of layer 16 using the CVD methodinvolves setting front glass substrate 11 inside a CVD apparatus andfeeding in a magnesium compound and oxygen as source chemicals in orderto induce a reaction. The source chemicals may be acetylacetonemagnesium (Mg(C₅H₇O₂)₂) and cyclopentadienyl magnesium (Mg(C₅H₅)₂), forexample.

[0056] 2. Manufacture of Back Panel 20

[0057] Address electrodes 22 are formed on back glass substrate 21 usingthe same screen-printing method as that employed in forming displayelectrodes 13 and 14.

[0058] Dielectric layer 23 is formed by using the screen-printing methodto apply a paste containing a lead-based glass material over addresselectrodes 22, and then baking the applied paste. It is also possible tomix TiO₂ particles in the paste to further enhance the reflection of thevisible light emitted from the phosphor layers 26R, 26G, and 26B.

[0059] Barrier ribs 24 are formed by using the screen-printing method torepeatedly apply a barrier rib paste composed of a glass material overdielectric layer 23, and then baking the applied barrier rib paste. Thebarrier ribs thus formed are microscopic in size and have a porouscomposition.

[0060] Reflective layer 25 is formed by using the inkjet method to applyreflective layer ink in the gap between adjacent barrier ribs 24 inwhich phosphor layer 26B is to be formed, and then drying the appliedreflective layer ink.

[0061] Phosphor layers 26R, 26G, and 26B are formed by using the inkjetmethod to apply phosphor ink in the gaps between adjacent barrier ribs24, and then baking the applied phosphor layer ink. A detaileddescription of the manufacture of reflective layer 25 and phosphorlayers 26R, 26G, and 26B is given in a later section.

[0062] In the present invention, the height and pitch of the barrierribs are both set at 0.15 mm as required in a 40-inch class high-visiontelevision.

[0063] 3. Sealing of the Panels

[0064] The PDP is constructed by (i) using a sealing layer glass to sealtogether front panel 10 and back panel 20 around the perimeter of thepanels, and (ii) filling a high vacuum (e.g. 8×10⁻⁷ Torr) created withinspaces partitioned by barrier ribs 24 with a discharge gas (e.g. aninert gas mixture of He—Xe or Ne—Xe) at a predetermined pressure (e.g.66.5-106 kPa) to form discharge spaces 27.

[0065] To achieve image display, the PDP is driven using drive circuitsmounted as shown in FIG. 4.

[0066] 4. Formation of Reflective Layer 25

[0067] Reflective layer 25 is formed by using an inkjet method to applyreflective layer ink in the gap between adjacent barrier ribs 24 inwhich phosphor layer 26B is to be formed, and then drying the appliedink.

[0068] The reflective layer ink is composed of TiO₂ particles,dielectric glass particles, a binder, a solvent, and a plasticizer thatare ground to a suitable viscosity using, for example, a three-rollmill.

[0069] In order to reduce the occurrence of nozzle clog and particledeposits, the TiO₂ particles preferably should have an average particlesize in a range of 0.05 μm to 2.0 μm inclusive. Also, to optimize thereflectivity of the ink, the TiO₂ particles preferably should be presentat approximately 40 wt % of the ink solution.

[0070] For the same reasons given in regard to the TiO₂ particles, theaverage particle size of the dielectric glass particles preferablyshould be in a range of 0.1 μm to 1.0 μm inclusive.

[0071] The binder is a water-soluble resin that includes, for example,at least one member selected from the group consisting of hydroxypropylcellulose, hydroxyethyl cellulose, ethylhydroxyethyl cellulose,carboxymethyl cellulose, polyvinyl alcohol, and polyvinyl ether. Inorder to optimize the ink viscosity, the weight-average molecular weightof the one or more resins in the binder preferably should each be in arange of 30,000 to 100,000 inclusive, and the binder should be includedin a range of 1 wt % to 20 wt % inclusive of the ink solution.Hydroxypropyl cellulose (weight-average molecular weight: approx.80,000) and hydroxyethyl cellulose are particularly suitable for use inthe binder.

[0072] The solvent preferably should be composed of water, or awater-miscible alcohol or alcohol derivative. If the solvent is awater-miscible alcohol or alcohol derivative, the solvent may include atleast one member selected from the group consisting of ethylene glycol,ethylene glycol monoacetate, ethylene glycol monoethyl ether, ethyleneglycol monobutyl ether, ethylene glycol monomethyl ether, ethyleneglycol monomethyl ether acetate, 3-methoxy-3-methylbutanol,allylalcohol, isopropyl alcohol, ethanol, glycidol, tetrahydrofurfurylalcohol, t-buthanol, furfuryl alcohol, propargyl alcohol, 1-propanol,methanol, 3-methyl-1-butyne-3-ol, 15-crown-5, 18-crown-6, propyleneoxide, 1,4-dioxane, dipropyl ether, dimethyl ether, tetrahydrofuran,acetaldehyde, diacetone alcohol, methyl lactate, γ-butyl lactone,glycerin, glycerin-1,2-dimethyl ether, glycerin-1,3-dimethyl ether,glycerin-1-acetate, 2-chloro-1,3-propanediol, 3-chloro-1,2-propanediol,diethylene glycol, diethylene glycol ethyl methyl ether, diethyleneglycol chlorohydrin, diethylene glycol diacetate, diethylene glycoldiethyl ether, diethylene glycol dimethyl ether, diethylene glycolmonomethyl ether, dipropylene glycol, dipropylene glycol monomethylether, and triethylene glycol. The appropriate solvent should bedetermined according to the viscosity of the ink and the solubility ofthe binder. In terms of the present embodiment, a particularly suitablemixture would include at least one member selected from the groupconsisting of ethylene glycol monomethyl ether acetate, ethylene glycol,3-methoxy-3-methylbutanol, and ethylene glycol monobutyl ether. Thesolvent preferably should be present at approximately 50 wt % of the inksolution.

[0073] The plasticizer may be at least one member selected from thegroup consisting of dimethyl phthalate, diethyl phthalate, dibutylphthalate, diheptyl phthalate, di-n-octyl phthalate, di-2-ethylhexylphthalate, octyldecyl phthalate, diisodecyl phthalate, and butylbenzylphthalate. To achieve a favorable leveling of the ink, the plasticizerpreferably should be included in a range of 0.5 wt % to 10 wt %inclusive of the ink at the time of application. At concentrations below0.5 wt % not enough leveling occurs, and at concentrations above 10% toomuch leveling occurs. In terms of the present embodiment, it isparticularly desirable for the plasticizer to include approximately 6 wt% dibutyl phthalate in order to optimize the viscosity and levelingqualities of the ink.

[0074] The viscosity of the reflective layer ink preferably should be ina range of 0.3 Pa.s (300 cP) to 50 Pa.s (50,000 cP) inclusive. Atviscosities of less than 0.3 Pa.s the applied ink is too thin tomaintain the desired form, and at viscosities of greater than 50 Pa.sthe applied ink is too viscous to be effectively discharged from thenozzle of the ink application apparatus. In terms of the presentembodiment, the optimal viscosity is approximately 3.5 Pa.s.

[0075]FIG. 5 is a schematic structural view of an ink applicationapparatus 50 used in forming reflective layer 25.

[0076] As shown in FIG. 5, an ink server 51 stores the reflective layerink, and a pressure pump 52 supplies the ink to an ink head 53 byapplying pressure to the stored ink. Ink head 53 includes an ink chamber53 a and a nozzle 54, and the ink supplied to ink chamber 53 a isejected in a continuous stream from nozzle 54. A plurality of nozzles 54is provided (only one depicted in FIG. 5) so as to allow for the pluralapplication of reflective layer ink at any one time.

[0077] Ink head 53 is formed in one piece (i.e. to include both inkchamber 53 a and nozzle 54) by machining and electrodischarge machininga metal material.

[0078] The aperture of nozzle 54 preferably should be 45 μm or greaterso as to prevent the nozzle from clogging. Generally, an aperture in arange of 45 μm to 150 μm inclusive is preferred, since the nozzleaperture is then smaller than the gap between adjacent barrier ribs 24.In terms of the present embodiment, a nozzle aperture of 100 μm is useddue to the rib gap being set at 150 μm.

[0079] In order to prevent the ink particles forming a deposit in inkserver 51, an agitator (not depicted) attached within the ink server isused to mix the stored ink.

[0080] The pressurization of pressure pump 52 is adjusted so that theink ejected from nozzle 54 flows in a continuous stream.

[0081] Ink head 53 scans over back glass substrate 21 in a directionparallel to barrier ribs 24. In the present embodiment, the scanning byink head 53 is conducted by a scan mechanism (not depicted) that drivesink head 53 in a linear direction over back glass substrate 21. However,ink head 53 may be fixed in place and back glass substrate 21 may bemoved in a linear direction under the fixed ink head 53.

[0082] Reflective layer ink is applied in the gap in which the bluephosphor layer 26B will be formed between adjacent barrier ribs 24 byejecting ink from nozzle 54 so as to form a continuous ink flow 55 (jetline) while scanning ink head 53 over back glass substrate 21 in adirection parallel to barrier ribs 24.

[0083] Moisture in the reflective layer ink and moisture absorbed fromthe air serves to prevent the ink from becoming charged as a result ofshearing stress caused when the ink particles (e.g. TiO₂ particles,dielectric glass particles, etc.) are discharged through the tubing andnozzle of ink application apparatus 50. The moisture in the ink and themoisture-absorbing qualities of the ink can be attributed to the binderbeing a water-soluble resin and the solvent being water or awater-miscible solvent. Since the charging of the reflective layer inkis prevented, the ink can be discharged accurately without thedeterioration in precision that occurs with prior art technology. As aresult, the ink can be applied as desired in the gap between adjacentbarrier ribs 24.

[0084]FIGS. 6A to 6D are schematic cross-sectional views of barrier ribs24 on back panel 20 that show the processes involved in forming thereflective and phosphor layers in the gap between adjacent barrier ribs24.

[0085] As shown in FIG. 6A, reflective layer ink 250 applied in the gap240 between barrier ribs 24 adheres in a “U” shape to the rib walls 241and base of gap 240 as a result of the force with which ink flow 55 isejected. When the ink is initially applied, the thickness W1 ofreflective layer ink 250 on rib walls 241 is greater than the thicknessW2 of the ink on the base of gap 240. Due to evaporation and also thedispersion of the solvent into rib walls 241 of the porous barrier ribs,the concentration of solvent in ink 250 is reduced after application. Onthe other hand, the greater molecular weight of the plasticizer incomparison to both alcohol and water, makes the plasticizer less proneto evaporation and dispersion, and therefore high concentrations ofplasticizer remain in the water-soluble resin after application. Theplasticizer helps to maintain the flexibility of the resin by weakeningthe coherence of the resin particles, and as a result the applied inklevels over time according to a process commonly known as “leveling.”

[0086] As shown in FIG. 6, downward forces F1 and sideward forces F2work on the particles (e.g. TiO₂ particles, dielectric glass particles,etc.) included in reflective layer ink 250. In particular, the sidewardforces F2 exert a great deal of force on the particles close to ribwalls 241.

[0087] The final form that the ink takes in the gap between barrier ribs24 is determined by balancing the gravitational forces F1 and F2. In theprior art, the ink is formed thicker on the rib walls 241 than on thebase of the gap because of the increased coherence of the resinparticles resulting from the reduction in solvent concentration levels.According to the present embodiment, however, a plasticizer is includedin ink 250, and this allows ink 250 to retain a low viscosity because ofthe plasticizer remaining in the ink after application, despite theevaporation and dispersion of the solvent. The coherence of the resinparticles is reduced as a result, and this allows for a reduction in thegravitation pull of sideward forces F2. Because of the leveling thatconsequently occurs, some of reflective layer ink 250 applied to ribwalls 241 is shifted, as shown in FIG. 6B, to the base of gap 240 bydownward forces F1. Consequently, the thickness of the ink on rib walls241 is reduced from W1 (FIG. 6A) to W3, and the ink thickness on thebase of gap 240 is increased from W2 (FIG. 6A) to W4. The aperture ratioof the PDP according to the present embodiment is thus increased incomparison to the prior art, and brightness levels are improved.

[0088] The formation of reflective layer 25 is completed by drying thereflective layer ink 250 applied as described above.

[0089] 5. Formation of the Phosphor Layers

[0090] The viscosity of the phosphor ink is adjusted as required byusing a three-roll mill to homogenize and disperse the phosphorparticles, binder, plasticizer, and solvent included in the ink.

[0091] The phosphor particles may be the same as those conventionallyused in the formation of PDP phosphor layers. For example, thecomposition of the red (R), green (G), and blue (B) phosphors may be asfollows:

[0092] Red phosphors: (Y_(x)Gd_(1−x))BO₃:Eu³+ or YBO₃:Eu³⁺

[0093] Green phosphors: BaAl₁₂O₁₉:Mn or ZnSiO₄:Mn

[0094] Blue phosphors: BaMgAl₁₀O₁₇:Eu²⁺

[0095] In order to reduce the occurrence of nozzle clog and particledeposits, the average particle size of the phosphor particles preferablyshould be less than or equal to 7 μm. Smaller phosphor particles help toenhance luminous efficiency and are therefore preferred, although forease of handling the phosphor particles preferably should have anaverage particle size of at least 0.5 μm. In terms of the presentembodiment, phosphor particles in a range of 0.5 μm to 7 μm inclusiveare suitable, although the preferred range is 2 μm to 3 μm inclusive. Inthe present embodiment, the phosphor particles are present atapproximately 43 wt % of the phosphor ink.

[0096] The binder included in the phosphor ink may be the same as thatused in the formation of reflective layer 25. In order to maintain asuitable viscosity of the phosphor ink, the binder preferably should beincluded in the ink in a range of 1 wt % to 20 wt % inclusive. In thepresent embodiment, the binder is present at approximately 5 wt % of thephosphor ink. A water-soluble resin may be used as the binder, and awater-soluble cellulose is preferred because of the minimal residueremaining after the ink is baked. Although cellulose is generallyconsidered to be fairly heat resistant due to its high decompositiontemperature, our experimentation has shown that almost no residueremains after the baking process, even at conventional bakingtemperatures.

[0097] The plasticizer included in the phosphor ink may be the same asthat used in forming reflective layer 25. In the present invention, itis particularly desirable for dibutyl phthalate to be present atapproximately 18 wt % of the ink so as to optimize the ink viscosity.

[0098] The solvent included in the phosphor ink may be the same as thatused in forming reflective layer 25. A solvent mixture includingethylene glycol monomethyl ether acetate, ethylene glycol,3-methyl-3-methoxybutanol, and butyl carbitol is particularly suitable.The solvent preferably should be present at approximately 34 wt % of thephosphor ink.

[0099] The phosphor ink is manufactured by dissolving the binder in thesolvent, adding suitable quantities of phosphor particles andplasticizer, and grinding the mixture using a three-roll mill. Theviscosity of the phosphor ink preferably should be in a range of 0.3Pa.s (300 cP) to 50 Pa.s (50,000 cP) inclusive. At viscosities of lessthan 0.3 Pa.s the applied ink is too thin to maintain the desired form,and at a viscosities of greater than 50 Pa.s the applied ink is tooviscous to be effectively discharged from the nozzle of the inkapplication apparatus. In particular, a viscosity in a range of 1 Pa.sto 50 Pa.s inclusive is preferred.

[0100] Phosphor ink 260 may be applied in the same way as reflectivelayer ink 250 using ink application apparatus 50.

[0101] Specifically, the phosphor ink may be applied between adjacentbarrier ribs 24 on back glass substrate 21 by ejecting the ink so as toform a continuous ink flow 55 (jet line) from nozzle 54 while scanningink header 53 over substrate 21 in a direction parallel to barrier ribs24. This process is repeated for each of the phosphor layers red (R),green (G), and blue (B), respectively. As a result, the red (R) andgreen (G) phosphor ink is applied as shown in FIG. 6A.

[0102] On the other hand, the blue (B) phosphor ink is applied onreflective layer 25 as shown in FIG. 6C. As with the application ofreflective layer 25, the application of the blue (B) phosphor inkresults in the ink thickness W5 on rib walls 241 being greater than theink thickness W6 on the base of gap 240.

[0103] In forming reflective layer 25, the inclusion of the plasticizerin phosphor ink 260 allows the ink to retain a low viscosity, despiteany evaporation or dispersion of the solvent. As a result of theleveling that consequently occurs, some of the ink 260 on the rib walls241 flows to the base of gap 240. As shown in FIG. 6D, the ink thicknesson the walls is reduced from W5 to W7, and the ink thickness on the baseis increased from W6 to W8.

[0104] The formation of phosphor layers 26R, 26G, and 26B is completedby drying the red, green, and blue phosphor inks applied respectively inpredetermined gaps between adjacent barrier ribs 24, and baking (approx.500° C. for 10 min.) the panel.

[0105] As a result of the baking process, most of the solvent in the inkis eliminated. Most of the binder in the ink is also eliminated despitethe decomposition temperature of the binder used in the presentembodiment being higher than that of conventional binders. Also, much ofthe plasticizer included in the ink either evaporates or is burnt off,and little remains after the baking process. To optimize luminousefficiency, the thickness of the phosphor layers 26R, 26G, and 26Bpreferably should be 10 to 20 times the average particle size of thephosphor particles in ink 260. The thickness the phosphor layers can beadjusted by adjusting the composition ratio of phosphor ink 260.

[0106] Effects of the Present Embodiment

[0107] As described above, when ink is applied using the inkjet method,the uneven adhesion of the ink can be reduced and the accuracy of theink discharged from the nozzle of the ink application apparatus can beimproved by using a water-soluble resin as the binder in the ink, andwater, a water-miscible alcohol derivative, or the alcohol derivativemixed with water as the solvent in the ink, and then adding aplasticizer to the ink.

[0108] In other words, because the solvent conventionally used in theink is not water-miscible, it is not possible to reduce the charging ofthe ink when the particles in the ink became charged. In comparison, thewater-miscibility of the solvent used in the present embodiment allowsthe ink to absorb moisture from the air, and thereby reduce any chargingthat occurs when the ink is ejected from the nozzle of the inkapplication apparatus. As a result, the accuracy of the ink ejected fromthe nozzle can be maintained. Furthermore, with the conventionalphosphor ink, the charging of the ink often results in a rise forming inthe phosphor layer over the point corresponding to the break in theaddress electrodes. However, the charging-prevention quality of the inkof the present embodiment allows for this rise to be eliminated.Moreover, by including the plasticizer in the ink, the low viscosity ofthe ink can be maintained, despite any reductions in solventconcentrations due to evaporation or dispersion of the solvent afterapplication. Consequently, by using the reflective layer ink andphosphor ink of the present invention, it is possible to achieve thedesired thickness of the reflective and phosphor layers on the ribwalls. As a result, increases in the cell aperture ratio of the PDP canbe realized.

[0109] Since the nozzle through which the phosphor ink is discharged isonly a couple of dozen nanometers in diameter, the use of conventionalsolvents and binders often leads to a gelling of non-dissolved particlesin the binder, and consequently the clogging of the nozzle. However, theexcellent dissolution qualities of the binder included in the phosphorink of the present embodiment allows for nozzle clogging to be reduced.As a result, the ink can be applied continuously over an extended periodof time.

[0110] In addition to the above effects, the water-soluble phosphor inkalso exhibits excellent characteristics in the washing process.Specifically, the use of the conventional organic phosphor ink requiresthat an organic solvent be used in the washing process, which raisesquestions relating to the environment and the treatment of wasteproducts, not to mention the safely and health of those handling thesolvent. In contrast, the water-soluble phosphor ink of the presentembodiment requires the use of only water and a minimal amount oforganic solvent in the washing process. Therefore, the handling of theink is considerably improved in comparison to the conventional organicphosphor ink, and environmental benefits are anticipated. Also, thephosphors washed away in the washing process can be collected easily andsafely.

EMBODIMENT EXAMPLES

[0111] Embodiment Samples 1 to 7

[0112] Embodiment sample PDPs 1 to 7 were manufactured in which thephosphor layers were formed by using an inkjet method to apply aphosphor ink that included, at the levels shown in Table 1, a powdermaterial, a water-soluble resin, a solvent, and a plasticizer, and thendrying and baking the applied ink. TABLE 1 Phosphors Resin SolventPlasticizer (wt %) (wt %) (wt %) (wt %) Comparative Sample 42 5 53 0Embodiment Sample 1 42 5 52.5 0.5 Embodiment Sample 2 42 5 52 1Embodiment Sample 3 42 5 51 2 Embodiment Sample 4 42 5 49 4 EmbodimentSample 5 42 5 45 8 Embodiment Sample 6 42 5 43 10 Embodiment Sample 7 425 41 12

[0113] The phosphors included in the phosphor ink were red phosphors (Y,Gd) BO₃:Eu, and the resin was ethylhydroxyethyl cellulose having aweight-average molecular weight of 80,000. The solvent was a mixturecontaining equals amounts of ethylene glycol monomethyl ether acetate,ethylene glycol, 3-methoxy-3-methylbutanol, and butyl carbitol. Theplasticizer was butyl phthalate.

[0114] The PDP was a 42-inch class model having barrier ribs 24 of 120μm in height and gaps between adjacent barrier ribs of 150 μm inbreadth. A reflective layer was not provided.

Comparative Sample

[0115] As shown in Table 1, a comparative sample PDP was manufacturedusing the same method as in embodiment samples 1 to 7, except that aplasticizer was not included in the phosphor ink.

[0116] Measured Results and Related Considerations

[0117] With respect to embodiment samples 1 to 7 and the comparativesample, the thickness of the phosphor layer was measured on the ribwalls (at a position 30 μm down from the top of the barrier ribs) and atthe base of the gap between adjacent barrier ribs. The measurementresults are shown in Table 2. TABLE 2 Phosphor Phosphor Layer ThicknessLayer Thickness (base) μm (rib wall) μm Comparative Sample 3-5 20-25Embodiment Sample 1 7-9 18-22 Embodiment Sample 2 10-17 17-21 EmbodimentSample 3 18-22 16-20 Embodiment Sample 4 26-28 14-18 Embodiment Sample 527-30 12-15 Embodiment Sample 6 28-30 12-15 Embodiment Sample 7 31-35 8-12

[0118] As shown by the results in Table 2, the thickness of the phosphorlayer on the rib walls is reduced and the thickness on the base of thegap between adjacent barrier ribs is increased for each of theembodiment samples in comparison to the comparative sample. Furthermore,the results show that the flexibility retained by the ink at plasticizerlevels of 0.5 wt % or greater allows some of the phosphors adhering tothe rib walls after the ink is applied to flow down to the base of thegap between adjacent barrier ribs. Plasticizer levels of 4 wt % to 8 wt% are shown to yield the best results, while plasticizer levels ofgreater than 10 wt % make the ink too flexible, resulting in an overlythin phosphor layer on the rib walls and an overly thick phosphor layeron the base of the gap between adjacent barrier ribs.

[0119] In the embodiment samples, the accuracy of the ink dischargedfrom the nozzle of the ink application apparatus using the inkjet methodis maintained. This effect is attributed to the fact that the phosphorink includes a water-soluble resin and a water-miscible solvent, whichallows the ink to absorbed moisture from the air ink when ejected fromthe nozzle of the ink application apparatus, thereby allowing any chargestored in the ink to be discharged.

[0120] Variations

[0121] In the embodiment as described above, the inkjet method and inkapplication apparatus 50 are used in forming reflective layer 25 andphosphor layers 26R, 26G, and 26B. However, the inkjet method and inkapplication apparatus 50 may also be used in to apply ink used in theformation of shading films 12, display electrodes 13 and 14, addresselectrodes 22, and the sealing layer, etc.

[0122]FIGS. 7A and 7B show the application of a silver electrode ink 220in forming an address electrode 22 of back panel 20.

[0123] As shown in FIG. 7A, the force at which silver electrode ink 220is discharged from ink application apparatus 50 (not depicted) is suchthat a cross-sectional view shows the outer sides of the applied ink tobe thicker than a middle area. If a plasticizer is not included insilver electrode ink 220, the viscosity of the ink will increase as thesolvent in the ink dries, and as a result address electrode 22 will beformed in the shape of the ink as initially applied. However, as shownin FIG. 7B, leveling of the applied ink occurs when a plasticizer isincluded in silver electrode ink 220, and a cross-sectional view showsthe ink to be evenly distributed. As a result, the formation ofelectrodes having an uneven thickness can be reduced.

[0124] The same effects as described above can be anticipated when theink is used to form shading films 12, display electrodes 13 and 14, andthe sealing layer.

[0125] The ink used in forming shading films 12 preferably should be amixture composed of (i) a black pigment that includes at least onemember selected from the group consisting of RuO, NiO, TiO, TiO—Al₂O₃,and iron oxide, (ii) a frit glass having an average particle size in arange of 0.1 μm to 1 μm inclusive, and (iii) the same solvent and binderused in forming reflective layer 25 and phosphor layers 26R, 26G, and26B. In particular, if the gross weight of the binder included in theink exceeds 20 wt %, the ink will be too viscous, and thus the flow ofthe ink from the nozzle of the ink application apparatus will beinhibited. Conversely, if the gross weight of the binder is less than 1wt %, the ink will not be viscous enough, and thus the applied ink willnot retain the desired form. As such, the binder preferably should beincluded in a range of 1 wt % to 20 wt % inclusive of the ink.

[0126] The ink used in forming the display electrodes and addresselectrodes preferably should be a mixture composed of silver particleshaving an average particle size of 0.5 μm to 3 μm, and the same binderand solvent used in forming reflective layer 25 and phosphor layers 26R,26G, and 26B. For the same reasons given above in regard to theformation of shading films 12, the binder preferably should be includedin a range of 1 wt % to 20 wt % inclusive of the ink.

[0127] The ink used in forming the sealing layer preferably should be amixture composed of frit glass having an average particle size of 0.1 μmto 1 μm, and the same binder and solvent used in forming reflectivelayer 25 and phosphor layers 26R, 26G, and 26B. For the same reasonsgiven above in regard to the formation of the shading films 12, thebinder preferably should be included in a range of 1 wt % to 20 wt %inclusive of the ink. The sealing layer is formed by using an inkjetmethod to apply the ink around the perimeter of one of the front paneland the back panel.

[0128] The present invention is also applicable, for example, in formingthe backlight of a liquid crystal display (LCD) panel. In this case, thenozzle of the ink application apparatus preferably should be a slitnozzle, and a phosphor ink composed of a mixture of red, green, and bluephosphors that radiates a white light preferably should be applied tothe panel surface of the LCD.

[0129] According to this structure, the same effects as described abovefor the embodiment of the present invention can be achieved.

[0130] Industrial Applicability

[0131] The ink of the present invention is applicable in the manufactureof display panels used in computers, televisions, and the like, and isparticularly suitable for use in the manufacture of display panelsrequiring high definition.

1. An ink for a display panel that is applied to a substrate of thedisplay panel using an inkjet method, comprising: a powder material usedin forming a structural layer of the display panel; water or awater-miscible solvent; a binder formed from a water-soluble resin; anda plasticizer.
 2. The ink of claim 1, wherein the binder is included ina range of 1 wt % to 20 wt % inclusive of the ink at a time ofapplication.
 3. The ink of claim 2, wherein the plasticizer is includedin a range of 0.5 wt % to 10 wt % inclusive of the ink at a time ofapplication.
 4. The ink of claim 2, wherein the structural layer is aphosphor layer, and the powder material includes phosphor particleshaving an average particle size in a range of 0.5 μm to 7 μm inclusive.5. The ink of claim 2, wherein, the structural layer is a reflectivelayer, and the powder material includes a white pigment having anaverage particle size in a range of 0.05 μm to 2 μm inclusive, and aglass frit material having an average particle size in a range of 0.1 μmto 3 μm inclusive.
 6. The ink of claim 5, wherein the white pigmentincludes at least one member selected from the group consisting oftitanium oxide, barium nitride, and alumina oxide.
 7. The ink of claim2, wherein the structural layer is a silver electrode, and the powdermaterial includes a silver particle material having an average particlesize in a range of 0.1 μm to 3 μm inclusive, and a glass frit materialhaving an average particle size in a range of 0.1 μm to 1 μm inclusive.8. The ink of claim 2, wherein the structural layer is a shading film,and the powder material includes a black pigment, and a glass fritmaterial having an average particle size in a range of 0.1 μm to 1 μminclusive.
 9. The ink of claim 8, wherein the black pigment includes atleast one member selected from the group consisting of RuO, NiO, TiO,TiO—Al₂O₃, and iron oxide.
 10. The ink of claim 2, wherein thestructural layer is a sealing layer, and the powder material includes aglass frit material having an average particle size in a range of 0.1 μmto 3 μm inclusive.
 11. The ink of claim 2, wherein the water-solubleresin includes at least one member selected from the group consisting ofhydroxypropyl cellulose, hydroxyethyl cellulose, ethylhydroxyethylcellulose, carboxymethyl cellulose, polyvinyl alcohol, and polyvinylether, and has a weight-average molecular weight in a range of 30,000 to100,000 inclusive.
 12. The ink of claim 2, wherein the water-misciblesolvent includes at least one member selected from the group consistingof ethylene glycol, ethylene glycol monoacetate, ethylene glycolmonoethyl ether, ethylene glycol monobutyl ether, ethylene glycolmonomethyl ether, ethylene glycol monomethyl ether acetate,3-methoxy-3-methylbutanol, allylalcohol, isopropyl alcohol, ethanol,glycidol, tetrahydrofurfuryl alcohol, t-buthanol, furfuryl alcohol,propargyl alcohol, 1-propanol, methanol, 3-methyl-1-butyne-3-ol,15-crown-5, 18-crown-6, propylene oxide, 1,4-dioxane, dipropyl ether,dimethyl ether, tetrahydrofuran, acetaldehyde, diacetone alcohol, methyllactate, γ-butyl lactone, glycerin, glycerin-1,2-dimethyl ether,glycerin-1,3-dimethyl ether, glycerin-1-acetate,2-chloro-1,3-propanediol, 3-chloro-1,2-propanediol, diethylene glycol,diethylene glycol ethyl methyl ether, diethylene glycol chlorohydrin,diethylene glycol diacetate, diethylene glycol diethyl ether, diethyleneglycol dimethyl ether, diethylene glycol monomethyl ether, dipropyleneglycol, dipropylene glycol monomethyl ether, and triethylene glycol. 13.The ink of claim 2, wherein the plasticizer includes at least one memberselected from the group consisting of dimethyl phthalate, diethylphthalate, dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate,di-2-ethylhexyl phthalate, octyldecyl phthalate, diisodecyl phthalate,and butylbenzyl phthalate.
 14. A manufacturing method for a plasmadisplay panel that includes a first panel and a second panel, the methodhaving a structural layer formation step of forming a structural layerof the first panel, and a sealing step of sealing the first panel to thesecond panel and filling a space between the sealed panels with a gasmedium, wherein the structural layer formation step has: an applicationsubstep of applying an ink for a display panel to the first panel usingan inkjet method, the ink including a powder material used in formingthe structural layer, water or a water-miscible solvent, a binder formedfrom a water-soluble resin, and a plasticizer; and a baking substep ofburning-off the binder and the plasticizer included in the applied ink.15. A manufacturing method for a plasma display panel that includes apanel having a plurality of porous barrier ribs formed in rows, themethod having a reflective layer formation step of forming a reflectivelayer in a rib gap between adjacent barrier ribs, wherein the reflectivelayer formation step has: an application substep of applying thereflective layer ink of claim 5 in the rib gap using the inkjet method;and a baking substep of burning-off the binder and the plasticizerincluded in the applied reflective layer ink.
 16. The manufacturingmethod of claim 15, wherein a viscosity of the reflective layer ink isin a range of 0.3 Pa.s to 50 Pa.s inclusive.
 17. A manufacturing methodfor a plasma display panel that includes a panel having a plurality ofporous barrier ribs formed in rows, the method having a phosphor layerformation step of forming a phosphor layer in a rib gap between adjacentbarrier ribs, wherein the phosphor layer formation step has: anapplication substep of applying the phosphor ink of claim 4 in the ribgap using the inkjet method; and a baking substep of burning-off thebinder and the plasticizer included in the applied phosphor ink.
 18. Themanufacturing method of claim 17, wherein a viscosity of the phosphorink is a range of 1 Pa.s to 50 Pa.s inclusive.
 19. A manufacturingmethod for a plasma display panel that includes a panel, the methodhaving a shading film formation step of forming a shading film on aprinciple surface of the panel, wherein the shading film formation stephas: an application substep of applying the shading film ink of claim 8to the principle surface of the panel using the inkjet method; and abaking substep of burning-off the binder and the plasticizer included inthe applied shading film ink.
 20. A manufacturing method for a plasmadisplay panel that includes a panel, the method having a silverelectrode formation step of forming a silver electrode on a principlesurface of the panel, wherein the silver electrode formation step has:an application substep of applying the silver electrode ink of claim 7to the principle surface of the panel using the inkjet method; and abaking substep of burning-off the binder and the plasticizer included inthe applied silver electrode ink.
 21. A manufacturing method for aplasma display panel that includes a panel, the method having a sealinglayer formation step of forming a sealing layer around a perimeter ofthe panel, wherein the sealing layer formation step has: an applicationsubstep of applying the sealing layer ink of claim 10 to the perimeterof the panel using the inkjet method; and a baking substep ofburning-off the binder and the plasticizer included in the appliedsealing layer ink.